H2 – CH4 blending fuels combustion using a cyclonic burner on colorless distributed combustion

H₂ – CH₄ mixture fuels can be promising for reducing carbon-based emissions. However, because of higher pollutant emission (such as NO_X) problems during hydrogen combustion, a new combustion method can be favorable. Colorless distributed combustion (CDC) is emerging here. CDC enables ultra-low pollutant emissions along with reduced flame instabilities, combustion noise, improved combustion efficiency, etc. Considering those benefits, methane and the hydrogen-enriched methane (60% CH₄ – 40% H₂, 50% CH₄ – 50% H₂, 40% CH₄ – 60% H₂) fuels have been consumed using a cyclonic burner providing more residence time at an equivalence ratio of 0.83 under distributed regime. For the modelings, Reynolds Stress Model (RSM) turbulence model, the assumed-shape with β-function Probability Density Function combustion model, and P-1 radiation model have been selected. To seek CDC, the oxygen concentration in the oxidizer was reduced with N₂ or CO₂ diluent from 21% O₂ to 13% O₂ at an interval of 2%. The air and the fuel temperatures were kept constant at 300 K. Besides, for seeking high-temperature air combustion (HiTAC) conditions the oxidizer temperature was changed to 600 K to simulate flue gas recirculation. The results showed that the temperature distributions changed to be more uniform considerably with a decrease in oxygen concentration for all cases. CDC also provided a considerable decrease in NO_X and a favorable reduction in CO at a certain oxygen concentration. It has been concluded that CO₂ as the diluent was more effective for reducing temperature levels and NO_X levels due to its greater heat capacity.